Hydraulic pressure supply system of automatic transmission

ABSTRACT

A hydraulic pressure supply system of an automatic transmission for a vehicle may include a low-pressure hydraulic pump driven by an electric motor, generating low hydraulic pressure using oil stored in an oil pan, and supplying the low hydraulic pressure to a low pressure portion and a cooler, and a high-pressure hydraulic pump driven by the electric motor, increasing a portion of the low hydraulic pressure to high hydraulic pressure, and supplying the high hydraulic pressure to a high pressure portion through a high-pressure line fluid-connecting the high-pressure hydraulic pump to the high pressure portion, wherein a pressure sensor for detecting the low hydraulic pressure supplied to the cooler may be disposed at an input side of the cooler, and a rotation speed of the electric motor may be controlled based on the low hydraulic pressure detected by the pressure sensor.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No. 10-2012-0121837 filed on Oct. 31, 2012, the entire contents of which is incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hydraulic pressure supply system of an automatic transmission for a vehicle. More particularly, the present invention relates to a hydraulic pressure supply system of an automatic transmission for a vehicle which can prevent unnecessary hydraulic pressure loss by controlling a rotation speed of an electric motor based on hydraulic pressure supplied to a cooler.

2. Description of Related Art

Recently, vehicle makers direct all their strength to improve fuel economy due to worldwide high oil prices and strengthen of exhaust gas regulations.

Improvement of fuel economy may be achieved by minimizing unnecessary power consumption of a hydraulic pump.

A recent automatic transmission is provided with a low-pressure hydraulic pump and a high-pressure hydraulic pump so as to improve fuel economy. Therefore, hydraulic pressure generated by the low-pressure hydraulic pump is supplied to a low pressure portion (i.e., a torque converter, a cooling device, and a lubrication device), and hydraulic pressure generated by the high-pressure hydraulic pump is supplied to a high pressure portion (i.e., friction members selectively operated when shifting).

In further detail, general hydraulic pressure of the automatic transmission is generated for the low pressure portion (i.e., generated by the low-pressure hydraulic pump), and hydraulic pressure demanded by the high pressure portion is generated by the high-pressure hydraulic pump and then is supplied to the high pressure portion.

FIG. 1 is a schematic diagram of a conventional hydraulic pressure supply system of an automatic transmission for a vehicle.

Referring to FIG. 1, a conventional hydraulic pressure supply system is adapted to supply low hydraulic pressure generated by a low-pressure hydraulic pump 2 to a low pressure portion 4 such as a torque converter (T/C), a cooling portion, and a lubrication portion, and to supply high hydraulic pressure generated by a gh-pressure hydraulic pump 6 to a high pressure portion 8 for operating friction members related to shifting.

The hydraulic pressure generated by the low-pressure hydraulic pump 2 is controlled to be stable hydraulic pressure at a low-pressure regulator valve 10 and is then supplied to the low pressure portion 4, and the low-pressure regulator valve 10 is controlled by control pressure of a first solenoid SOL1.

If the high-pressure hydraulic pump 6 increases the low hydraulic pressure supplied from the low-pressure hydraulic pump 2 to high hydraulic pressure, and the hydraulic pressure increased by the high-pressure hydraulic pump 6 is controlled to be stable hydraulic pressure by a high-pressure regulator valve 12 and is then supplied to the high pressure portion 8.

In addition, a first hydraulic pressure sensor S1 for detecting the hydraulic pressure is disposed on a low-pressure line 14 connecting the low-pressure hydraulic pump 2 to the low-pressure regulator valve 10, and a second hydraulic pressure sensor S2 for detecting the hydraulic pressure is disposed on a high-pressure line 16 connecting the high-pressure hydraulic pump 6 to the high-pressure regulator valve 12.

Therefore, a rotation speed of an electric motor M that is a drive source is controlled according to signals detected by the first and second hydraulic pressure sensors S1 and S2.

Since the first and second hydraulic pressure sensors S1 and S2 are used for controlling the rotation speed of the electric motor M, however, the number of components may increase and manufacturing cost may also increase according to a conventional hydraulic pressure supply system.

In addition, since the first and second hydraulic pressure sensors S1 and S2 do not detect spare hydraulic amount of the low-pressure line 14 and the high-pressure line 16 but detect whether target pressure is reached, the rotation speed of the electric motor M cannot be controlled optimally.

The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing a hydraulic pressure supply system of an automatic transmission for a vehicle having advantages of reducing unnecessary hydraulic pressure loss and enhancing fuel economy by controlling a rotation speed of an electric motor based on hydraulic pressure supplied to a cooler in the hydraulic pressure supply system of the automatic transmission using two hydraulic pumps driven by the electric motor.

In an aspect of the present invention, a hydraulic pressure supply system of an automatic transmission for a vehicle may include a low-pressure hydraulic pump driven by an electric motor, generating low hydraulic pressure using oil stored in an oil pan, and supplying the low hydraulic pressure to a low pressure portion and a cooler, and a high-pressure hydraulic pump driven by the electric motor, increasing a portion of the low hydraulic pressure to high hydraulic pressure, and supplying the high hydraulic pressure to a high pressure portion through a high-pressure line fluid-connecting the high-pressure hydraulic pump to the high pressure portion, wherein a pressure sensor for detecting the low hydraulic pressure supplied to the cooler is disposed at an input side of the cooler, and a rotation speed of the electric motor is controlled based on the low hydraulic pressure detected by the pressure sensor.

The low-pressure hydraulic pump and the high-pressure hydraulic pump are connected to each other by one shaft and are driven by the electric motor.

The low-pressure hydraulic pump receives the oil stored in the oil pan through an input line fluid-connecting the low-pressure hydraulic pump and the oil pan, generates the low hydraulic pressure, discharges the low hydraulic pressure to a first low-pressure line fluid-connected to the low-pressure hydraulic pump and the high-pressure hydraulic pump.

The hydraulic pressure supply system may include a low-pressure regulator valve fluid-connected to the first low-pressure line and controlling the low hydraulic pressure supplied from the first low-pressure line to be a stable low hydraulic pressure, wherein the low-pressure regulator valve supplies the stable low hydraulic pressure to the low pressure portion and the cooler through a second low-pressure line fluid-connecting the low-pressure regulator valve to the low pressure portion and the cooler respectively.

The low-pressure regulator valve is controlled by elastic force of an elastic member disposed at a side thereof and the low hydraulic pressure of the first low-pressure line supplied to an opposite side to the elastic member, wherein the low-pressure regulator valve recirculates a portion of the low hydraulic pressure supplied through the first low-pressure line to the input line through a first recirculation line fluid-connecting the low-pressure regulator valve and the input line so as to control the low hydraulic pressure.

The high-pressure hydraulic pump increases a portion of the low hydraulic pressure supplied through the first low-pressure line to the high hydraulic pressure and discharges the high hydraulic pressure to the high-pressure line.

The hydraulic pressure supply system may further include a high-pressure regulator valve fluid-connected to the high pressure line and controlling the high hydraulic pressure supplied from the high-pressure line to be a stable high pressure, wherein the high-pressure regulator valve supplies the stable high hydraulic pressure to the high pressure portion.

The high-pressure regulator valve is controlled by control pressure of a solenoid valve applying to a side thereof, elastic force of an elastic member disposed at the side thereof, and a portion of the high hydraulic pressure in the high-pressure line applying to the other side thereof, wherein the high-pressure regulator valve recirculates a portion of the high hydraulic pressure supplied through the high-pressure line to the second low-pressure line through a second recirculation line fluid-connecting the high-pressure regulator valve and the second low pressure line so as to control the high hydraulic pressure.

The pressure sensor is mounted on the second low-pressure line connected to the cooler.

In another aspect of the present invention, a hydraulic pressure supply system of an automatic transmission for a vehicle which generates low hydraulic pressure and high hydraulic pressure using oil stored in an oil pan and supplies the low hydraulic pressure and the high hydraulic pressure respectively to a low pressure portion and a high pressure portion, may include a low-pressure hydraulic pump receiving the oil stored in the oil pan through an input line fluid-connecting the low-pressure hydraulic pump to the oil pan, generating the low hydraulic pressure, and discharging the low hydraulic pressure to a first low-pressure line fluid-connected to the low-pressure hydraulic pump, a low-pressure regulator valve fluid-connected to the first low-pressure line and controlled by elastic force of an elastic member disposed at a side thereof and the low hydraulic pressure of the first low-pressure line supplied to the other side thereof, recirculating a portion of the low hydraulic pressure supplied through the first low-pressure line to the input line through a first recirculation line fluid-connecting to the low-pressure regulator valve to the input line, and supplying a controlled low hydraulic pressure to the low pressure portion and a cooler through a second low-pressure line fluid-connecting the low-pressure regulator valve to the low pressure portion and the cooler, a high-pressure hydraulic pump fluid-connected to the low-pressure hydraulic pump through the first low-pressure line and increasing a portion of the low hydraulic pressure supplied through the first low-pressure line and discharging the high hydraulic pressure to a high-pressure line fluid-connected to the high-pressure hydraulic pump, a high-pressure regulator valve fluid-connected to the high-pressure line and controlled by control pressure of a solenoid valve applying to a side thereof, elastic force of an elastic member disposed at the side thereof, and the high hydraulic pressure of the high-pressure line applying to the other side thereof, recirculating a portion of the high hydraulic pressure supplied through the high-pressure line to the second low-pressure line through a second recirculation line fluid-connecting the high-pressure regulator valve and the second low-pressure line so as to control the high hydraulic pressure, and supplying a controlled high hydraulic pressure to the high pressure portion, a pressure sensor disposed on the second low-pressure line connected to the cooler, and an electric motor operating the low-pressure hydraulic pump and the high-pressure hydraulic pump based on the stable low hydraulic pressure in the second low-pressure line detected by the pressure sensor.

The low-pressure hydraulic pump and the high-pressure hydraulic pump are connected to each other by one shaft and are driven by the electric motor.

The methods and apparatuses of the present invention may have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a conventional hydraulic pressure supply system of an automatic transmission.

FIG. 2 is a schematic diagram of a hydraulic pressure supply system of an automatic transmission according to an exemplary embodiment of the present invention.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that the present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

An exemplary embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings.

Description of components that are not necessary for explaining the present exemplary embodiment will be omitted, and the same constituent elements are denoted by the same reference numerals in this specification.

In the detailed description, ordinal numbers are used for distinguishing constituent elements having the same terms, and have no specific meanings.

FIG. 2 is a schematic diagram of a hydraulic pressure supply system of an automatic transmission according to an exemplary embodiment of the present invention.

Referring to FIG. 2, a hydraulic pressure supply system according to an exemplary embodiment of the present invention is adapted to supply low hydraulic pressure generated by a low-pressure hydraulic pump 102 to a low pressure portion 104 such as a torque converter (T/C), a cooling portion, a lubrication portion and to supply high hydraulic pressure generated by a high-pressure hydraulic pump 106 to a high pressure portion 108 for operating friction members related to shifting.

The low hydraulic pressure is a lower pressure facilitating operation of the torque converter (T/C) and cooling and lubrication, and the high hydraulic pressure is a high pressure facilitating operation of a plurality of friction members.

The low-pressure hydraulic pump 102 and the high-pressure hydraulic pump 106 are connected to each other by one shaft and are driven by an electric motor M. The electric motor M is controlled by a transmission control unit.

The hydraulic pressure generated by the low-pressure hydraulic pump 102 is controlled to be stable hydraulic pressure by a low-pressure regulator valve 110 and is then supplied to the low pressure portion 104. For this purpose, the low-pressure hydraulic pump 102 receives oil stored in an oil pan P through an input line 112, and discharges the low hydraulic pressure to a first low-pressure line 114.

The low-pressure regulator valve 110 is controlled by elastic force of an elastic member 116 disposed at a side thereof and the hydraulic pressure of the first low-pressure line 114 supplied to the opposite side to the elastic member 116. The low-pressure regulator valve 110 recirculates a portion of the hydraulic pressure supplied through the first low-pressure line 114 to the input line 112 through a first recirculation line 118 so as to control the hydraulic pressure.

The high-pressure hydraulic pump 106 increases a portion of the low hydraulic pressure supplied from the low-pressure hydraulic pump 102 to the high hydraulic pressure, and discharges the high hydraulic pressure to a high-pressure line 120. The hydraulic pressure of the high-pressure line 120 is controlled by a high-pressure regulator valve 122 and is then supplied to the high pressure portion 108.

The high-pressure regulator valve 122 is controlled by control pressure of a solenoid valve SOL supplied to a side thereof, elastic force of an elastic member 124 disposed at the side thereof, and the hydraulic pressure of the high-pressure line 120 supplied to the other side thereof. The high-pressure regulator valve 122 recirculates a portion of the hydraulic pressure supplied through the high-pressure line 120 to a second low-pressure line 130 through a second recirculation line 126 so as to control the hydraulic pressure.

The second low-pressure line 130 connects the low-pressure regulator valve 110 to the low pressure portion 104 and to a cooler 132 such that the stable low hydraulic pressure controlled by the low-pressure regulator valve 110 is supplied to the low pressure portion 104 and the cooler 132.

In addition, the low-pressure hydraulic pump 102 and the high-pressure hydraulic pump 106 are connected to each other by the one shaft and are driven by the electric motor M.

In the hydraulic pressure supply system of an automatic transmission according to an exemplary embodiment of the present invention, a pressure sensor S is disposed on the second low-pressure line 130 connected to the cooler 132.

The pressure sensor S detects the hydraulic pressure supplied to the cooler 132 and transmits information thereon to the transmission control unit, and the transmission control unit compares a predetermined hydraulic pressure with the detected hydraulic pressure and controls the rotation speed of the electric motor M.

That is, the transmission control unit compares the hydraulic pressure of the cooler 132 detected by the pressure sensor S with the predetermined hydraulic pressure, and controls to decrease, maintain, or increase the rotation speed of the electric motor M based on driving conditions (e.g., RPM, oil temperature, line variable current, and so on).

Therefore, hydraulic amount pumped by the low-pressure hydraulic pump 102 and the high-pressure hydraulic pump 106 driven by the electric motor M is so controlled that unnecessary hydraulic pressure loss can be prevented.

That is, since the hydraulic pressure supplied to the cooler 132 converges to hydraulic pressure at a specific rotation speed, rise of the rotation speed of the electric motor M to a rotation speed faster than the specific rotation speed is not effective on cooling and lubrication. In this case, hydraulic pressure may be lost unnecessarily, and accordingly fuel economy may be deteriorated.

Since the electric motor M is controlled based on the hydraulic pressure supplied to the cooler 132 in an exemplary embodiment of the present invention, the hydraulic pressure may be managed effectively.

Since the rotation speed of the electric motor is controlled based on the hydraulic pressure supplied to the cooler in the hydraulic pressure supply system of the automatic transmission using two hydraulic pumps driven by the electric motor, unnecessary hydraulic pressure loss may be prevented and accordingly fuel economy may be enhanced according to an exemplary embodiment of the present invention.

For convenience in explanation and accurate definition in the appended claims, the terms “upper”, “lower”, “inner” and “outer” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents. 

What is claimed is:
 1. A hydraulic pressure supply system of an automatic transmission for a vehicle comprising: a low-pressure hydraulic pump driven by an electric motor, generating low hydraulic pressure using oil stored in an oil pan, and supplying the low hydraulic pressure to a low pressure portion and a cooler; and a high-pressure hydraulic pump driven by the electric motor, increasing a portion of the low hydraulic pressure to high hydraulic pressure, and supplying the high hydraulic pressure to a high pressure portion through a high-pressure line fluid-connecting the high-pressure hydraulic pump to the high pressure portion, wherein a pressure sensor for detecting the low hydraulic pressure supplied to the cooler is disposed at an input side of the cooler, and a rotation speed of the electric motor is controlled based on the low hydraulic pressure detected by the pressure sensor.
 2. The hydraulic pressure supply system of claim 1, wherein the low-pressure hydraulic pump and the high-pressure hydraulic pump are connected to each other by one shaft and are driven by the electric motor.
 3. The hydraulic pressure supply system of claim 1, wherein the low-pressure hydraulic pump receives the oil stored in the oil pan through an input line fluid-connecting the low-pressure hydraulic pump and the oil pan, generates the low hydraulic pressure, discharges the low hydraulic pressure to a first low-pressure line fluid-connected to the low-pressure hydraulic pump and the high-pressure hydraulic pump.
 4. The hydraulic pressure supply system of claim 3, further comprising: a low-pressure regulator valve fluid-connected to the first low-pressure line and controlling the low hydraulic pressure supplied from the first low-pressure line to be a stable low hydraulic pressure, wherein the low-pressure regulator valve supplies the stable low hydraulic pressure to the low pressure portion and the cooler through a second low-pressure line fluid-connecting the low-pressure regulator valve to the low pressure portion and the cooler respectively.
 5. The hydraulic pressure supply system of claim 4, wherein the low-pressure regulator valve is controlled by elastic force of an elastic member disposed at a side thereof and the low hydraulic pressure of the first low-pressure line supplied to an opposite side to the elastic member, and wherein the low-pressure regulator valve recirculates a portion of the low hydraulic pressure supplied through the first low-pressure line to the input line through a first recirculation line fluid-connecting the low-pressure regulator valve and the input line so as to control the low hydraulic pressure.
 6. The hydraulic pressure supply system of claim 4, wherein the high-pressure hydraulic pump increases a portion of the low hydraulic pressure supplied through the first low-pressure line to the high hydraulic pressure and discharges the high hydraulic pressure to the high-pressure line.
 7. The hydraulic pressure supply system of claim 6, further comprising: a high-pressure regulator valve fluid-connected to the high pressure line and controlling the high hydraulic pressure supplied from the high-pressure line to be a stable high pressure, wherein the high-pressure regulator valve supplies the stable high hydraulic pressure to the high pressure portion.
 8. The hydraulic pressure supply system of claim 7, wherein the high-pressure regulator valve is controlled by control pressure of a solenoid valve applying to a side thereof, elastic force of an elastic member disposed at the side thereof, and a portion of the high hydraulic pressure in the high-pressure line applying to the other side thereof, and wherein the high-pressure regulator valve recirculates a portion of the high hydraulic pressure supplied through the high-pressure line to the second low-pressure line through a second recirculation line fluid-connecting the high-pressure regulator valve and the second low pressure line so as to control the high hydraulic pressure.
 9. The hydraulic pressure supply system of claim 4, wherein the pressure sensor is mounted on the second low-pressure line connected to the cooler.
 10. A hydraulic pressure supply system of an automatic transmission for a vehicle which generates low hydraulic pressure and high hydraulic pressure using oil stored in an oil pan and supplies the low hydraulic pressure and the high hydraulic pressure respectively to a low pressure portion and a high pressure portion, the hydraulic pressure supply system comprising: a low-pressure hydraulic pump receiving the oil stored in the oil pan through an input line fluid-connecting the low-pressure hydraulic pump to the oil pan, generating the low hydraulic pressure, and discharging the low hydraulic pressure to a first low-pressure line fluid-connected to the low-pressure hydraulic pump; a low-pressure regulator valve fluid-connected to the first low-pressure line and controlled by elastic force of an elastic member disposed at a side thereof and the low hydraulic pressure of the first low-pressure line supplied to the other side thereof, recirculating a portion of the low hydraulic pressure supplied through the first low-pressure line to the input line through a first recirculation line fluid-connecting to the low-pressure regulator valve to the input line, and supplying a controlled low hydraulic pressure to the low pressure portion and a cooler through a second low-pressure line fluid-connecting the low-pressure regulator valve to the low pressure portion and the cooler; a high-pressure hydraulic pump fluid-connected to the low-pressure hydraulic pump through the first low-pressure line and increasing a portion of the low hydraulic pressure supplied through the first low-pressure line and discharging the high hydraulic pressure to a high-pressure line fluid-connected to the high-pressure hydraulic pump; a high-pressure regulator valve fluid-connected to the high-pressure line and controlled by control pressure of a solenoid valve applying to a side thereof, elastic force of an elastic member disposed at the side thereof, and the high hydraulic pressure of the high-pressure line applying to the other side thereof, recirculating a portion of the high hydraulic pressure supplied through the high-pressure line to the second low-pressure line through a second recirculation line fluid-connecting the high-pressure regulator valve and the second low-pressure line so as to control the high hydraulic pressure, and supplying a controlled high hydraulic pressure to the high pressure portion; a pressure sensor disposed on the second low-pressure line connected to the cooler; and an electric motor operating the low-pressure hydraulic pump and the high-pressure hydraulic pump based on the stable low hydraulic pressure in the second low-pressure line detected by the pressure sensor.
 11. The hydraulic pressure supply system of claim 10, wherein the low-pressure hydraulic pump and the high-pressure hydraulic pump are connected to each other by one shaft and are driven by the electric motor. 